1. Field of the Invention
This invention relates to a fluid injection assembly designed to be used in combination with a flowing stream of liquid whereby metered quantities of a fluid may be injected into the flowing stream. Means are provided for observing both the rate of flow of the flowing stream and the rate of injection of the fluid, and, furthermore, for varying the rate of fluid injection with regard to the flow rate of the flowing stream.
2. Description of the Prior Art
Chemical and fluid injection systems of various types are known and utilized in numerous applications. More specifically, such prior art systems are utilized for the injection of various types of chemicals into bodies of water or other liquids wherein the injection of such chemicals occurs over a predetermined period of time and at a relatively consistent rate. Such applications include, but are obviously not limited to, chemical injection for the purpose of purification of drinking water, treatment of water with fertilizers, pesticides, etc., for agricultural purposes, and the injection of fertilizers and distribution of pesticides for other varied applications of domestic and commercial agricultural purposes.
Another application of such an injection system involves the fluid dispensing of various food products in individual doses such as coin or demand activated vending machines used to dispense various types of liquid foodstuffs.
As stated above, numerous types of prior art or conventional injection assembly structures are known. However, it has frequently been found that the performance and operating characteristics of such prior art devices are less than desirable and in some cases are ineffective or inefficient. Another problem associated with the use of such injection assemblies involves the necessity for use of an outside power source to operate an activating mechanism such as a pump, or the like, for the material being injected. It should be obvious that such auxiliary or supplementary power forms add both to the expense and maintenance service attributable to these prior art devices.
Two exemplar prior art devices are shown in U.S. Pat. No. 2,618,510 to Mills and U.S. Pat. No. 3,187,769, to McDowell, et al. Both of these prior art devices basically depend upon the flow rate of the primary liquid, such as water, to regulate the injection rate of the treatment fluid. However, it is well known that the actual rate of flow of the liquid into which chemicals are to be injected may vary from time to time. Accordingly, as the flow rate of the liquid varies, so will the injection rate of the treatment fluid. This will necessarily result in dispensed concentrations of varying strength.
Accordingly, there is an obvious and recognized need for a fluid injection assembly which is capable of wide and varied applications and which comprises a structure which is relatively maintenance free and relatively unsophisticated, thereby decreasing the cost of initial purchase and the time and money consumed in maintaining the assembly. Such a structure should also be efficient in its operation and sufficiently versatile in its operating characteristics so as to allow its use in a wide variety of applications. The structure of such an assembly should also be capable of allowing the dispensing of a given fluid without the need or use of an auxiliary power source such as a pump mechanism, or the like. In order to provide for relatively constant dispensed solution concentrations, the assembly should also include means for monitoring the flow rate of the liquid into which chemicals are being injected and corresponding means for varying the injection rate dependent upon the liquid's actual flow rate and the desired final concentration.